A water-based composition with low volatile organic (VOC) content such as a paint, seal, coat, caulk, etc. is exposed to contamination from the atmosphere from the moment it is applied. This contamination includes dirt and dust which are carried to the surface by rain, airborne moisture droplets, wind currents, or direct physical contact with people, animals, or other objects. Dirt can be either organic or inorganic. Examples of dirt particles include sand, smoke particles, dust, metallic fibers, carbon black, rust, grease, pollen, human detritus, and fungal spores. Dirt particles attract moisture to the surface of the composition. This moisture provides a suitable environment in which microbial spores may survive and proliferate into colonies, thus further contributing to the unsightly appearance of the surface. Accordingly, water-based compositions can acquire a dirty and unsightly appearance because of the amount of dirt that clings to them. Similarly, paints used on exterior masonry walls or wood siding often experience staining and paint loss as a result of efflorescence, tannin bleed-through, surfactant leaching, and other effects.
Previously, the paint industry has used compounds like benzophenone to aid in the dirt pickup resistance of water-based paints, specifically water-based acrylic coatings. However, there is a general desire in the industry to reduce VOC emissions to at or near-zero levels, thereby reducing the environmental and health impact of paints. Benzophenone is considered a VOC and its use as a dirt pickup resistance additive in water-based paints increases the VOC emissions of the paint.
Accordingly, there is a need for effective low VOC compositions that resist dirt pick up and resist efflorescence, surfactant leaching, tannin bleed-through and other similar effects when used as exterior durable paints, and do not compromise the required application and performance properties desirable for finished surfaces in the paint industry.